<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style media="screen">
    .table {
      width: 100%;
    }
    .table th,.table td {
      /*width: 20px;*/
      height: 40px;
      line-height: 40px;
      text-align: center;
      border-bottom: 1px solid #757575;
      border-right: 1px solid #757575;
    }
    .table th{
      border-top: 1px solid #757575;
    }
    .table th:first-child,.table tr td:first-child{
      border-left: 1px solid #757575;
    }
  </style>
</head>
<body>
  <table class="table" cellspacing="0" cellpadding="0">
    <thead>
      <tr>
        <th>姓名</th>
        <th>性别</th>
        <th>年龄</th>
      </tr>
    </thead>
    <tbody>
       <tr>
         <td>张三</td>
         <td>男</td>
         <td>18</td>
       </tr>
       <tr>
         <td>张三</td>
         <td>男</td>
         <td>18</td>
       </tr>
       <tr>
         <td>张三</td>
         <td>男</td>
         <td>18</td>
       </tr>
       <tr>
         <td>张三</td>
         <td>男</td>
         <td>18</td>
       </tr>
       <tr>
         <td>张三</td>
         <td>男</td>
         <td>18</td>
       </tr>
       <tr>
         <td>张三</td>
         <td>男</td>
         <td>18</td>
       </tr>
    </tbody>
  </table>
</body>
</html>
